The present invention relates to the field of roof coverings, in particular a modular roof covering system which extends longevity of traditional roofing membranes, restores and protects the environment, moderates and helps control building temperature, manages stormwater runoff and collects and utilizes solar energy.
To maintain a comfortable interior space at a low cost, many advances have been made in roofing and insulation technology. Most developments have been made in the materials which are placed in the attic space such as slurried or rolled insulation. There has been relatively little development in materials applied to the exterior surfaces of roofs. As costs for energy and concerns over the environment increase, there is an increasing demand for low cost, energy efficient methods to reduce the amount of energy needed to maintain a comfortable living and work space, particularly in existing buildings where the costs of most modem solutions can be prohibitive.
To address these concerns, additional roofing coverage has been placed over the standard or existing roofing materials for added thermal insulation. One example of additional roofing coverage is vegetation. A covering of vegetation on a roof structure provides a layer of insulation that helps keep the building interior cool in the summer and warm in the winter. Most modem turf covering methods or systems use a layer of soil and a complex system of multi-layered materials to protect the underlying structure from damage. This type of construction is expensive, can add a significant amount of weight to the roof, and may require significant modification to the roof or physical attachment to the roof structure. Because of the high costs and undesirable weight additions of most current systems, many existing buildings cannot utilize these systems.
The present invention provides a light weight and low cost alternative for roof coverings to extend longevity of traditional roofing membranes, restore and protect the environment, moderate and help control building temperature, manage stormwater runoff and collect and utilize solar energy.
The present invention uses a series of modular interlocking trays or containers which hold several functional layers, which vary from embodiment to embodiment depending on the design requirement for the particular application. The trays are interlocked with each other, or otherwise connected to each other to cover a large area on a roof or other surface. Additionally, the trays are ballasted or weighted down without being physically connected to the roof surface on which they are positioned.
In the first embodiment, the top layer in the modular trays is a layer which consists of vegetation, such as grass or sedum species, which is selected to accommodate the climate in which the system is used and address any aesthetic intentions or requirements. Under the top layer is a lightweight soil matrix layer to support the plant growth, by providing support for the roots. Below the soil matrix layer is a filter layer to prevent erosion of the soil matrix layer and to remove particulate and other matter from the water runoff, and a water-capture area (in the tray) to mitigate storm water runoff.
The trays are ballasted or weighted down by any commonly known or used method, but preferably by paving stones which are laid in spaces created by the interconnection of the trays. In addition to providing ballast, the paving stones also provide a means to move about the roof without stepping into or otherwise disturbing the vegetation growing in the trays. Optionally, in this embodiment, an irrigation or sprinkler system can be installed to provide water irrigation for the vegetation or additional cooling for the building. This is particularly applicable to hotter and dryer climates. In this embodiment the modules may be pre-assembled, requiring only installation of the modules on the roof or other surface, or the vegetation may be added after the modules are placed in position through the use of seeds, cuttings, or root formed plugs.
In the second embodiment, there is also a series of functional layers. In this embodiment, the top layer consists of a permeable membrane rather than vegetaion that allows water to flow through. Below the top membrane is a reservoir designed to capture, hold and slowly release precipitation and moisture through evaporation and/or drainage (when the membrane becomes saturated). In an alternative embodiment, the reservoir contains an absorbent or super absorbent polymer (xe2x80x9cSAPxe2x80x9d) to further increase the water absorption and/or reduce runoff. Below the reservoir layer is a roof drainage layer, that holds the layers positioned above it above the roofing membrane. The roof drainage layer allows excess precipitation to flow off of the roof, without compromising the integrity of the modules or the layers positioned therein. It is noted that although this embodiment includes the interlocking modular trays previously discussed, the functional layers may be enclosed in moisture absorbent bags which are secured together, without the use of the trays. A sprinkler system may be installed to provide moisture to the functional layers of this system depending on the climate and system requirements. Further, any suitable ballast or weighting system can be used to provide support and security for this embodiment.
The third embodiment of the present invention uses modular trays to support a top layer consisting of a housing or structure holding an array of (or single) photovoltaic cells or panels and drainage holes. The housing allows the cells or array to pivot and/or rotate thereby tracking the sun for optimum performance of the cells or array. Below the array or cell housing is a reservoir designed to capture, hold and slowly release moisture or precipitation through drainage and/or evaporation. This reservoir function is similar to, and can be, the same structure and method described above in the second embodiment.
Because the underlying modules or trays for each of the above embodiments can be the same, a roofing system can be installed which utilizes a combination of any of the above embodiments. The present invention is not limited to the use of a single embodiment in any one roofing system.
The present invention provides a low-cost, low-weight system for moderating building temperature and increasing the useful life of roof coverings and structure while at the same time reducing energy use and environmental impact.